1. Field of the Invention
The present invention relates to a technique for determining a sleeping state of a user.
2. Description of the Related Art
Users play games by wearing a body-mounted display device such as a head mounted display (hereinafter, referred to as a “HMD”) connected to a game device, and operating a controller or the like while seeing a screen displayed on the HMD.
For a normal stationary type display connected to a game device, a user can see objects outside a screen of the display. Thus, sometimes, the user cannot concentrate on the screen of the display, or the user cannot be immersed in the game. On the other hand, if the user wears the HMD, the user cannot see objects except a screen image displayed on the HMD. Thus, the user can be immersed in a screen image world, and the user can enjoy the game more.
However, if the game progresses while the user who wears the HMD falls asleep, a disadvantageous situation may occur in the game, or data of the situation of the game before the user falls asleep cannot be saved even though the user hopes to have the data stored. As a result, when the user wakes up, an unintended (undesired) situation of the game may occur.
Thus, a technique is known in which whether a user is in a sleeping state is determined based on whether the user closes his/her eyes, and a predetermined process is performed based on the determined result (see Patent Document 1 and Patent Document 2, for example). For example, Patent Document 1 describes detecting whether a user is in a sleeping state from open-close information of eyes, and displaying images, that were displayed from the time when the sleeping state is detected to the time when the end of the sleeping state is detected, again when the end of the sleeping state is detected. Patent Document 2 describes determining whether a viewer is in a sleeping state or in a gazing state based on whether the viewer closes his/her eyes by irradiating invisible light beam on the eyes of the viewer. Then, when it is determined to be the sleeping state, an alarm is displayed or the like and power is switched off.
However, sometimes, a user may close his/her eyes for a while when the user has tired eyes or the like. Thus, whether the user is in the sleeping state may be wrongly determined if it is determined based on just by tracking the eyes of the user.